Niosomal Gel 7. 1 INTRODUCTION

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1 7. 1 INTRODUCTION Niosomes or non-ionic surfactant vesicles are microscopic lamellar structures formed on admixture of non-ionic surfactant of the alkyl or dialkylpolyglycerol ether class and cholesterol with subsequent hydration in aqueous media. They are vesicular systems similar to liposomes that can be used as carriers of amphiphilic and lipophilic drugs. The method of preparation of niosome is based on liposome technology. The basic process of preparation is the same i.e. hydration by aqueous phase of the lipid phase which may be either a pure surfactant or a mixture of surfactant with cholesterol. After preparing niosomal dispersion, unentrapped drug is separated by dialysis centrifugation or gel filtration. A method of in-vitro release rate study includes the use of dialysis tubing. Niosomes are promising vehicle for drug delivery and being non-ionic; it is less toxic and improves the therapeutic index of drug by restricting its action to target cells. Niosomes are unilamellar or multilamellar vesicles formed from synthetic non-ionic surfactants. They are very similar to the liposomes. Niosomal drug delivery is potentially applicable to many pharmacological agents for their action against various diseases. Niosomes have shown promise in the release studies and serve as a better option for drug delivery system. This class of vesicles was introduced by Handjani Vila et al. They are vesicular systems similar to liposomes that can be used as carriers of amphiphilic and lipophilic drugs 1. One of the reasons for preparing niosomes is the assumed higher chemical stability of the surfactants than that of phopholipids, which are used in the preparation of liposomes. Due to the presence of ester bond, phospholipids are easily hydrolysed. 2,3 Unreliable reproducibility arising from the use of lecithins in liposomes leads to additional problems and has led scientist to search for vesicles prepared from other material, such as nonionic surfactants. Niosomes are promising vehicle for drug delivery and being non-ionic; it is less toxic and improves the therapeutic index of drug by restricting its action to target cells. Niosomes or non-ionic surfactant vesicles are microscopic lamellar structures formed on admixture of non-ionic surfactant of the alkyl or dialkylpolyglycerol ether class and cholesterol with subsequent hydration in aqueous media. 4 In niosomes, the vesicles forming amphiphile is a non-ionic surfactant such as Span 60 which is usually stabilized by addition of cholesterol and small amount of anionic surfactant such as dicetyl phosphate. The first report of non- Institute of Pharmaceutical Sciences, Kurukshetra University, Kurukshetra 151

2 ionic surfactant vesicles came from the cosmetic applications devised by L Oreal. 5 The concept of incorporating the drug into niosomes for a better targeting of the drug at appropriate tissue destination is widely accepted by researchers and academicians. Niosomes represent a promising drug delivery module. They present a structure similar to liposome and hence they can represent alternative vesicular systems with respect to liposomes, due to the niosome ability to encapsulate different type of drugs within their multi-environmental structure. 6 Niosomes are thoughts to be better candidates drug delivery as compared to liposomes due to various factors like cost, stability etc. Various type of drug deliveries can be possible using niosomes like targeting, ophthalmic, topical, parentral, etc. 3 Structure of Niosomes Niosomes are lamellar structures that are microscopic in size. They constitute of nonionic surfactant of the alkyl or dialkylpolyglycerol ether class and cholesterol with subsequent hydration in aqueous media. The surfactant molecules tend to orient themselves in such a way that the hydrophilic ends of the non-ionic surfactant point outwards, while the hydrophobic ends face each other to form the bilayer as we can see in fig.1. This figure gives a better idea of the lamellar orientation of the surfactant molecules. Fig.1: Diagrammatic representation of a niosomes 4 The non-ionic surfactants form a closed bilayer vesicle in aqueous media based on its amphiphilic nature using some energy for instance heat, physical agitation to form this structure. In the bilayer structure, hydrophobic parts are oriented away from the aqueous solvent, whereas the hydrophilic heads remain in contact with the aqueous Institute of Pharmaceutical Sciences, Kurukshetra University, Kurukshetra 152

3 solvent. The properties of the vesicles can be changed by varying the composition of the vesicles, size, lamellarity, tapped volume, surface charge and concentration. Various forces act inside the vesicle like Vander Waals forces among surfactant molecules, repulsive forces emerging from the electrostatic interactions among charged groups of surfactant molecules, entropic repulsive forces of the head groups of surfactants, short-acting repulsive forces etc. These forces are responsible for maintaining the vesicular structure of niosomes. But, the stability of niosomes are affected by type of surfactant, nature of encapsulated drug, storage temperature, detergents, use of membrane spanning lipids, the interfacial polymerization of surfactant monomers in situ, inclusion of charged molecule 3. Niosomes may act as a depot, releasing the drug in a controlled manner. The therapeutic performance of the drug molecules can also be improved by delayed clearance from the circulation, protecting the drug from biological environment and restricting effects to target cells. 5 It can also be used as vehicle for poorly absorbable drugs to design the novel drug delivery system. It enhances the bioavailability by crossing the anatomical barrier of gastrointestinal tract via transcytosis of M cells of Peyer's patches in the intestinal lymphatic tissues. 6 The niosomal vesicles are taken up by reticulo-endothelial system. Such localized drug accumulation is used in treatment of diseases, such as leishmaniasis, in which parasites invade cells of liver and spleen. 3,27 Some nonreticulo- endothelial systems like immunoglobulins also recognize lipid surface of this delivery system. 3-5,9,10,27,29,30 Encapsulation of various anti-neoplastic agents in this carrier vesicle has minimized drug-induced toxic side effects while maintaining, or in some instances, increasing the antitumour efficacy. 13 Many drugs are administered through niosomes via transdermal route to improve the therapeutic efficacy. Niosomes provides better drug concentration at the site of action administered by oral, parenteral and topical routes. The evolution of niosomal drug delivery technology is still at the stage of infancy, but this type of drug delivery system has shown promise in cancer chemotherapy and antileishmanial therapy : ADVANTAGES OF NIOSOMES The niosomal drug delivery is a potential drug delivery method for controlled and targeted drug delivery, the major advantages of these vesicular drug carriers are; Institute of Pharmaceutical Sciences, Kurukshetra University, Kurukshetra 153

4 Niosomal dispersion in an aqueous phase can be emulsified in a non-aqueous phase to regulate the delivery rate of drug and administer normal vesicle in external non-aqueous phase. The vesicle suspension is water based vehicle. This offers high patient compliance in comparison with oily dosage forms. They are osmotically active and stable, as well as they increase the stability of entrapped drug. Handling and storage of surfactants requires no special conditions. They improve oral bioavailability of poorly absorbed drugs and enhance skin penetration of drugs. They can be made to reach the site of action by oral, parenteral as well as topical routes. The surfactants are biodegradable, biocompatible and non-immunogenic. Niosomal dispersion in an aqueous phase can be emulsified in a non-aqueous phase to regulate the delivery rate of drug and administer normal vesicle in external non-aqueous phase. Niosomes possess an infrastructure consisting of hydrophilic, amphiphilic and lipophilic moieties together. They can be used for a variety of drugs. These are flexible in their nature so can be easily modulated. They improve the therapeutic performance of the drug by protecting it from the biological environment and restricting effects to target cells, thereby reducing the clearance of the drug. Niosomes offer a controlled release of drug. They can enhance the skin penetration of drugs. Handling and storage of surfactants very easy. The vesicle suspension being water based comply patients need : FACTORS AFFECTING NIOSOMES FORMULATION a) Nature of encapsulated Drug Entrapment of drug in niosomes increases vesicle size, probably by interaction of Institute of Pharmaceutical Sciences, Kurukshetra University, Kurukshetra 154

5 solute with surfactant head groups, increasing the charge and mutual repulsion of the surfactant bilayers, thereby increasing vesicle size. In polyoxyethylene glycol (PEG) coated vesicles, some drug is entrapped in the long PEG chains, thus reducing the tendency to increase the size. The hydrophilic lipophilic balance of the drug affects degree of entrapment. 12 Table 7.1: Effect of the nature of drug on the formation of niosomes Nature of the Leakage from the Stability Other properties drug vesicles Hydrophobic drug Hydrophobic drug Decreased Increased Improved transdermal Delivery Increased Decreased Amphiphilic drug Decreased - Increased encapsulation, Altered elecrophoretic mobility Macromolecules Decreased Increased (b) Nature of Surfactants A surfactant used for preparation of niosomes must have a hydrophilic head and hydrophobic tail. The hydrophobic tail may consist of one or two alkyl or perfluoroalkyl groups or in some cases a single steroidal group. 17 The ether type surfactants with single chain alkyl as hydrophobic tail is more toxic than corresponding dialkyl ether chain. 16 The ester type surfactants are chemically less stable than ether type surfactants and the former is less toxic than the latter due to ester-linked surfactant degraded by esterases to triglycerides and fatty acid In vivo 16. The surfactants with alkyl chain length from C12-C18 are suitable for preparation of niosomes 14,. 15 Surfactants such as C16EO5 (polyoxyethylenecetyl ether) or C18EO5 (polyoxyethylenesteryl ether) are used for preparation of polyhedral vesicles.span series surfactants having HLB number of between 4 and 8 can form vesicles. 18. Institute of Pharmaceutical Sciences, Kurukshetra University, Kurukshetra 155

6 Table 7.2: Different Types of Non-Ionic Surfactant Type of Non-ionic surfactant Fatty alcohol Ethers Esters Block copolymers Examples Cetyl alcohol, Steryl alcohol, Cetosteryl alcohol, oleyl alcohol Brij, Decylglucoside, Lauryl glucoside, Octylglucoside, Triton X-100, Nonoxynol-9 Glyceryllaurate, Polysorbates, Spans Poloxamers (c) Structure of Surfactants The geometry of vesicle to be formed from surfactants is affected by its structure, which is related to critical packing parameters. On the basis of critical packing parameters of surfactants, we can predicate geometry of vesicle to be formed. Critical packing parameters can be defined using following equation, CPP (Critical Packing Parameters) = v/lc a0 Where v = hydrophobic group volume, lc = the critical hydrophobic group length, a0= the area of hydrophilic head group. From the critical packing parameter value type of miceller structure formed can be ascertained as given below, If CPP < ½, then formation of spherical micelles, If ½ < CPP < 1, then formation of bilayer micelles, If CPP > 1, then formation inverted micelles. d) Amount and type of surfactant The mean size of niosomes increases proportionally with increase in the HLB of surfactants like Span 85 (HLB 1.8) to Span 20 (HLB 8.6) because the surface free energy decreases with an increase in hydrophobicity of surfactant 12. The bilayers of the vesicles are either in the so-called liquid state or in gel state, depending on the temperature, the type of lipid or surfactant and the presence of other components such as cholesterol. In the gel state, alkyl chains are present in a well-ordered structure, and in the liquid state, the structure of the bilayers is more disordered. The surfactants and Institute of Pharmaceutical Sciences, Kurukshetra University, Kurukshetra 156

7 lipids are characterized by the gel-liquid phase transition temperature (TC). Phase transition temperature (TC) of surfactant also effects entrapment efficiency i.e. Span 60 having higher TC, provides better entrapment 20 e) Cholesterol content and charge Inclusion of cholesterol in niosomes increases its hydrodynamic diameter and entrapment efficiency. In general, the action of cholesterol is two folds; on one hand, cholesterol increases the chain order of liquid-state bilayers and on the other, cholesterol decreases the chain order of gel state bilayers. At a high cholesterol concentration, the gel state is transformed to a liquid ordered phase 19. An increase in cholesterol content of the bilayers resulted in a decrease in the release rate of encapsulated material and therefore an increase of the rigidity of the bilayers obtained. Presence of charge tends to increase the interlamellar distance between successive bilayers in multilamellar vesicle structure and leads to greater overall entrapped volume. f) Resistance to osmotic stress Addition of a hypertonic salt solution to a suspension of niosomes brings about reduction in diameter. In hypotonic salt solution, there is initial slow release with slight swelling of vesicles probably due to inhibition of eluting fluid from vesicles, followed by faster release, which may be due to mechanical loosening of vesicles structure under osmotic stress 4. g) Membrane Composition The stable niosomes can be prepared with addition of different additives along with surfactants and drugs. Niosomes formed have a number of morphologies and their permeability and stability properties can be altered by manipulating membrane characteristics by different additives. In case of polyhedral niosomes formed from C16G2, the shape of these polyhedral niosome remains unaffected by adding low amount of solulan C24 (cholesteryl poly-24- oxyethylene ether), which prevents aggregation due to development of steric hindrance. In contrast spherical Niosomes are formed by C16G2: cholesterol:solulan (49:49:2). The mean size of niosomes is Institute of Pharmaceutical Sciences, Kurukshetra University, Kurukshetra 157

8 influenced by membrane composition such as Polyhedral niosomes formed by C16G2: solulan C24 in ratio (91:9) having bigger size (8.0 ± 0.03mm) than spherical/tubular niosomes formed by C16G2: cholesterol:solulan C24 in ratio (49:49:2) (6.6±0.2mm). Addition of cholesterol molecule to niosomal system provides rigidity to the membrane and reduces the leakage of drug from noisome Transdermal Delivery of Drugs by Niosomes Slow penetration of drug through skin is the major drawback of transdermal route of delivery. An increase in the penetration rate has been achieved by transdermal delivery of drug incorporated in niosomes. Jayramanet al has studied the topical delivery of erythromycin from various formulations including niosomes or hairless mouse. From the studies, and confocal microscopy, it was seen that nonionic vesicles could be formulated to target pilosebaceous glands : EXPERIMENTAL WORK DONE 7.2.1: PREPARATION OF NIOSOMAL GELS Unilamellar vesicles were prepared by the conventional thin film hydration method. Precisely weighed amount of Drug, Non-ionic surfactant and cholesterol (ratio reported in table) were dissolved in15ml chloroform. The lipid mixture was added to a 100-mL rounded bottom flask, and the solvent was evaporated slowly under reduced pressure at a temperature of 60ºC by a rotary evaporator (Buchi) at 135rpm. The evaporation step was continued until almost all organic solvent was evaporated and a thin lipid film was deposited on the wall of the flask. The excess, non evaporated organic solvent was removed by keeping the flask in a desiccator under vacuum overnight. The lipid film was hydrated with 10 ml of Phosphate buffered saline (ph 7.4). The hydration was continued for 1 hr., while the flask was kept rotating at 60ºC in the rotary evaporator. The niosomal suspension was further hydrated at room temperature for 2 hrs in order to complete the swelling process. The niosomal suspension was kept to mature overnight at 4 C. Institute of Pharmaceutical Sciences, Kurukshetra University, Kurukshetra 158

9 S.No. Formulation code Table 7.3: Formulation of niosomal gel Surfactant Drug:Surfactant: Cholestrol Quantity(mg) Drug Surfactant Cholestrol 1 NG1 T60 1:0.5: NG2 1:1: NG3 1:1.5: NG4 S60 1:0.5: NG5 1:1: NG6 1:1.5: NG7 T20 1:0.5: NG8 1:1: NG9 1:1.5: NG10 S20 1:0.5: NG11 1:1: NG12 1:1.5: Evaluation of Niosomal gels Method of reproducibility: To Asses the reproducibility of film hydration method formulations were prepared several times and % entrapment efficiency was measured for each batch. Vesicle morphology: The prepared niosomal formulations were characterized for their morphology using Scanning Electron Microscopy (SEM). The SEM photographs are given Fig. 7.3 Vesicle Size: The prepared niosomal suspension was diluted to suitable extent with phosphate buffer and a drop of diluted niosomal suspension was placed on a glass slide and the average size of vesicles was measured using optical microscope. Institute of Pharmaceutical Sciences, Kurukshetra University, Kurukshetra 159

10 Entrapment Efficiency: Entrapment efficiency of niosomal formulations was determined by separating the unentrapped drug. Un-entrapped drug was separated by centrifugation method. Centrifugation of suitably diluted niosomal suspension was carried out at 12000rpm for 20min. The supernatant liquid was analyzed for un-entrapped drug by UV spectrophotometer at 322nm. % Encapsulation Efficiency = (Total drug- Free drug / Total drug) 100 In-vitro dissolution studies The dissolution test was performed using standard USP apparatus II with some modifications by using modified paddle using phosphate buffer of ph 7.4. The dissolution medium was phosphate buffer ph 7.4. The temperature was maintained at 37±0.50C. The rpm was 50. Samples of 10 ml was withdrawn at predetermined time intervals 0.5h, 1h, 2h, and up to 8hrs and replaced with fresh and preheated 37±0.50C buffer solution each time. Samples were measured spectrophotometrically at 322nm. The amount released was calculated from regression line of the standard curve developed in the same medium. Stability Studies: In the present study, the stability of the vesicles was determined by slightly modifying procedure given by Solanki et al. Optimized formulation preserved at refrigerated temperature (4-8±1 C) and room temperature (25±2 C) for 3months. After every month, shape, size and % entrapment efficiency of vesicles were measured. The results were compared with the initial size, shape and % entrapment efficiency of both samples and are tabulated in table Kinetics of Drug Release: The mechanism of KT release from niosomal formulations was determined using the following mathematical models: zero-order kinetics (cumulative % release vs time), first-order kinetics (log % drug remaining vs time), Higuchi kinetics (cumulative % drug release vs. square root of time), Korsmeyer - Peppas (log cumulative % drug release vs log time. The r2 and n values are calculated for the linear curves obtained by regression analysis of the above plots. The results tabulated in table 7.9. Institute of Pharmaceutical Sciences, Kurukshetra University, Kurukshetra 160

11 RESULTS AND DISCUSSION: Results of Vesicle size of ketorolac tromethamine proniosome are presented in (Table7.5), which indicated that Vesicle formed with Span is smaller in size than vesicle formed with Tweens; this is due to greater hydrophobicity of Spans than Tweens. It is indicated that increasing in hydrophobicity decreases surface energy of surfactants resulting in smaller vesicle size. [12] Size of vesicle was reduced when dispersion was agitated. The reason for this is the energy applied in agitation which results in breakage of larger vesicles to smaller vesicles. The size range was found to be from 2.19µm to 6.97µm. Table 7.4: Particle size and entrapment efficiency of niosomal formulations (NG1-NG12) S.NO. Formulation code Particle size ±S.D Entrapment efficiency ±S.D 1 NG ± ± NG ± ± NG ± ± NG ± ± NG ± ± NG ± ± NG ± ± NG ± ± NG ± ± NG ± ± NG ± ± NG ± ±0.53 Entrapment efficiency was found to be higher in case of niosome prepared with span60 than niosome prepared with Tween this is due to fact that Span 60 is more hydrophobic than Tween, which act as solid at room temperature and showed higher phase transition temperature (Tc), low HLB value and long alkyl chain length [15] and results are shown in (Table 7.5).Entrapment efficiency was higher in Span60 as compared to Span 20; and Tween 60 as compared to tween 20 because longer chain Institute of Pharmaceutical Sciences, Kurukshetra University, Kurukshetra 161

12 surfactant produces high entrapment. Surfactants with long alkyl chains generally give larger vesicles. This might be the reason for the higher entrapment efficiency of vesicles prepared with longer alkyl chain surfactants. Figure 7.2: %Entrapment efficiency of tween niosomal gel Figure7.3: %Entrapment efficiency of span niosomal gel Institute of Pharmaceutical Sciences, Kurukshetra University, Kurukshetra 162

13 Figure 7.4: SEM of Niosomes Institute of Pharmaceutical Sciences, Kurukshetra University, Kurukshetra 163

14 Table 7.5: Cumulative drug release of Niosomal formulations* (NG1-NG12) Time (hr) NG1 NG2 NG3 NG4 NG5 NG6 NG7 NG8 NG9 NG10 NG11 NG ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.47 *Average of three determination Institute of Pharmaceutical Sciences, Kurukshetra University, Kurukshetra 164

15 Table 7.6: % Cumulative Drug Permeation of formulations NG 1 -NG 12 S. No. Formulation Code % CDR (in 8 hr) 1 NG NG NG NG NG NG NG NG NG NG NG NG Figure 7.5: % Cumulative Drug Release of formulations NG 1 -NG 12 Institute of Pharmaceutical Sciences, Kurukshetra University, Kurukshetra 165

16 In vitro release studies are often performed to predict how a delivery system might work in an ideal situation as well as give some indications of its In vivo performance since drug release indicates the amount of drug available for absorption. In-vitro release of Span was high as compared to tween.the amount of release was found to be in order of Span20> Tween60> Tween20> Span60.This was due low phase transition temperature of Span 20. Span 20 showed the release in range of 1:1.5:1>1:1:1>1:0.5: %, 34.99%, 30.89% in 8hrs respectively. The release of KT from the niosomes of different surfactants was found dependent on the chain length of surfactants. As the chain length increases, the release gets sustained for longer duration Phase transition temperature of span 60, span 20 is 53 C and16 C, respectively [27]. The reduced permeation of SSD from niosomes of span 60 can be attributed to their high transition temperatures, which may have made them in a highly ordered gel state at the permeation temperature of 37 C. On the other hand, the lower transition temperatures of span 20 may have made them in the disordered liquid crystalline state and completely fluid, hence; they were more permeable for the drug at 37 C. Similar is the effect of phase transition temperature on the release of drug from the niosomes manufactured by using different tweens. As the concentration of surfactant is increased In vitro release was increased due to high entrapment. Figure 7.6:%cumulative drug release of formulations containing tween60 Institute of Pharmaceutical Sciences, Kurukshetra University, Kurukshetra 166

17 Figure 7.7:%cumulative drug release of formulations containing tween20 Figure 7.8:%cumulative drug release of formulations containing span 60 Institute of Pharmaceutical Sciences, Kurukshetra University, Kurukshetra 167

18 Figure 7.9:%cumulative drug release of formulations containing span 20 Figure 7.10: Comparative %cumulative drug release of formulations containing tween60 and span 60 Institute of Pharmaceutical Sciences, Kurukshetra University, Kurukshetra 168

19 Figure7.11: Comparative %cumulative drug release of formulations containing tween20 and span : Mathematical modeling to study the in-vitro permeation kinetics of optimized batche Curve fitting analysis on the release data was done to find out the proper drug release mechanism. Zero, First, Higuchi and Korsmeyer-Peppas equations were applied to optimized batch In vitro release data and correlation coefficients (r2) values were determined, which are shown in Table 7.9. From the results, one can conclude that, the drug got released from niosomes by Korsmeyer Peppas model. Table 7.7: Mathematical modeling of optimized batch Time(hr) %CDR %drug remained Log %CDR Log %drug remained log time time Institute of Pharmaceutical Sciences, Kurukshetra University, Kurukshetra 169

20 Figure 7.12: Graphical representation of In-vitro permeation data of optimized formulation NG 10 : Zero order kinetics Figure 7.13: Graphical representation of In-vitro permeation data of optimized formulation NG 10 : First order kinetics Institute of Pharmaceutical Sciences, Kurukshetra University, Kurukshetra 170

21 Figure 7.14: Graphical representation of In-vitro permeation data of optimized formulation NG 10 : Higuchi model Figure 7.15: Graphical representation of In-vitro permeation data of optimized formulation NG 10 : Korsmeyer Peppas model Institute of Pharmaceutical Sciences, Kurukshetra University, Kurukshetra 171

22 Table 7.8: Value of R 2 obtained from different kinetic models Formulation R 2 Code Zero order First order Higuchi model Korsmeyer Peppas model n NG Curve fitting analysis on the release data was done to find out the proper drug release mechanism. Zero, First, Higuchi and Korsmeyer-Peppas equations were applied to optimized batch In vitro release data and correlation coefficients (r2) values were determined, which are shown in Table 7.9. From the results, one can conclude that, the drug got released from niosomes by Korsmeyer Peppas model. [ Table 7.9: Stability studies of optimized batch Characteristics Before storage After 3month storage 4-8 C 25±2 C 45±2 C Vesicle Size 2.35± ± ± ±0.67 %Entrapment 90.35± ± ± ±1.08 The Stability study of optimized batch revealed that particle size was increased after 3months on increasing the temperature. On the other hand entrapment efficiency was decreased on increasing the temperature. The physical instability was found in niosomes which may be due to aggregation of vesicles on storage. CONCLUSION: The in-vitro release from optimized batch of niosomal gel was found to be 37.59% in 8hrs. From the study we concluded that Spans gave more release as compared to tweens. As concentration of surfactant increased, % release was increased. Upon storage due to less physical stability of conventional niosomes particle size increased. While entrapment efficiency was decreased on increasing the temperature. Proniosomes can be prepared to increase the stability of niosomes. Institute of Pharmaceutical Sciences, Kurukshetra University, Kurukshetra 172

23 REFERENCES 1. Theresa MA, Drugs published by Adis interna0tional Ltd., 1998; 56(5): Breimer DD and Speiser R.Topics in pharmaceutical Sciences.5 Elsevier Science Publishers, New York, USA. 1985: Handjani-Vila RM., Ribier A., Rondot B and Vanlerberghe G. Dispersions of lamellar phases of non-ionic lipids in cosmetic products. International JournalCosmetic Sciences. 1979; 1: Malhotra M., Jain NK. Noisome as Drug Carriers. Indian Drugs. 1994, 31(3): Buckton G, Harwood. Interfacial phenomena in Drug Delivery and Targeting Academic Publishers, Switzerland. 1995: Don A, Van H, Joke AB and Hans E. Non ionic surfactant vesicles containing estradiol for topical application. Centre for drug research. 1997: Parthasarathi G., Udupa N, Umadevi P. and Pillai GK. Niosome encapsulated of vincristine sulfate: improved anticancer activity with reduced toxicity in mice. Journal Drug Target. 1994; 2(2): Kiwada H, NimuraH, Kato,Y.Chem, Pharm. Bull. 1985, 33: Baillie AJ, Florence AT, Hume LR, Rogerson A, and Muirhead GT. The preparation and properties of niosomes-non-ionic surfactant vesicles. J. Pharm Pharmacol. 1985; 37(12): Chandraprakash K.S., Udupa N., Umadevi P. and Pillai G.K. Formulation and evaluation of Methotrexate niosomes. Indian. JournalPharmaceuticalSciences, 1992; 54 (5): Parthasarathi G., Udupa N, UmadeviP,Pillai GK. Niosome encapsulated of vincristine sulfate: improved anticancer activity with reduced toxicity in mice. Journal of Drug Targeting 1994; 2(2): Raja RA, Chandrashekhar GPillai GK and Udupa N. Antiinflammatory activity of Niosome encapsulated diclofenac sodium with Tween -85 in Arthitic rats. Indian Journal Pharmacology. 1994; (26): Institute of Pharmaceutical Sciences, Kurukshetra University, Kurukshetra 173

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26 34. Cummings J, Staurt JF. and Calman K.C. Determination of adriamycin, adriamycinol and their 7-deoxyaglycones in human serum by high-performance liquid chromatography. Journal of Chromatography.1984; 311: Brewer J.M., Alexander J.A. The adjuvant activity of non-ionic surfactant vesicles (niosomes) on the BALB/c humoral response to bovine serum albumin. Immunology. 1992; 75 (4) : Gregoriadis,G.Liposomes as immunological adjuvants; Antigen incorporation studies. Vaccine. (5).1987; Institute of Pharmaceutical Sciences, Kurukshetra University, Kurukshetra 176